This invention relates to wireless communications systems and, more particularly, to wireless communications between mobile units and base stations.
The basic mechanism in wireless communication systems for a base station and one or more mobile units to communicate is to exchange messages by utilizing a so-called segment. One such wireless system is the Orthogonal Frequency Division Multiplex (OFDM) system. A segment, as shown in FIG. 2 and further described below, is a combination of a time slot index and a waveform index. A time slot is a basic time unit having a unique time slot index associated with it. During any particular time slot interval there could be several waveforms that are transmitted and received that may or may not be orthogonal. Each waveform has a unique waveform index. Messages of particular interest in wireless communication systems are mobile unit requests on an uplink and base station pages on a downlink.
Typically, a mobile unit can tolerate delays in receiving a page message from a base station. However, a mobile unit when transmitting a request, must convey the request to the base station and receive a request response message as soon as possible to keep latency to a minimum.
Problems and limitations related to prior wireless communication system mobile unit and base station access request and page transmissions are addressed by employing an efficient unified approach for the transmission and detection of both access requests from a mobile unit and pages from a base station.
To this end, a mobile unit monitors for access requests and monitors a prescribed resource to detect if a page has been received. Upon detection of an access request, a corresponding request message is generated and transmitting substantially immediately to a base station, thereby minimizing latency in the access process. Concurrently, a base station monitors to determine if a page indication has been received and monitors a prescribed resource to determine if an access request message has been received. In this process, the processing of request messages takes precedence over the processing of pages. Upon detecting a received request message a request response message is generated and transmitted substantially immediately to the mobile unit, thereby also minimizing latency in the access process.
More specifically, the mobile unit monitors prespecified signal assignment (A) segments for page messages from a base station. Upon receiving a page message, the mobile unit transmits an appropriate acknowledgment message to the base station and then performs the action specified in the received page message. If an access request is received, a request message is generated and transmitted to the base station substantially immediately in a request (R) segment in a time slot dedicated to the particular mobile unit. Then, the mobile unit monitors all received A-segments for a request response message from the base station. Upon receiving the request response message an appropriate acknowledgment message is transmitted in an ACK-segment to the base station. Then, the mobile unit performs the action specified in the received request response message. The mobile unit simultaneously monitors for both the page messages and the access requests and the processing of access requests takes precedence over processing of received page messages.
In a base station, if a page indication is received an appropriate page message is transmitted in an assigned A-segment to the mobile unit. Upon receiving a corresponding acknowledgment message from the mobile unit, the base station performs the action specified in the page message. If an access request message is detected in assigned R-segments, the base station generates and transmits substantially immediately an appropriate request response message to the mobile unit. Then, upon receiving an appropriate acknowledgment message from the mobile unit, the base station performs the action specified in the received request message. The base station simultaneously monitors for both the request messages and the pages and processing of received access request messages takes precedence over processing of page indications.
Thus, applicants"" unique invention employs this unified technique to address both the page and access request processes that balances their divergent requirements.